BACKGROUND: Propofol can produce a dose-dependent reduction in blood pressure by providing titratable sedation and rapid recovery. It has been reported that a combination of midazolam and propofol resulted in the significant reduction in the total dose of propofol needed. It was hypothesized that the addition of low-dose midazolam to propofol may provide sufficient sedation without compromising the hemodynamic stability. METHODS: A total of 40 consecutive patients were randomly assigned to one of two groups (n = 20 each). Group M-P received a bolus of 0.02 mg/kg of midazolam, followed by a propofol infusion with a fixed target concentration of 1.0microgram/ml. Group P received only a propofol infusion with an initial target plasma concentration of 2.5microgram/ml. Subsequent titration of the infusion rates in Group P or the additional midazolam boluses in Group M-P were made in order to maintain a predetermined sedation level. RESULTS: In Group P, a mean dose of 5.4 +/- 0.7 mg/kg/h propofol was used compared with 2.7 +/- 0.5 mg/kg/h in Group M-P (P<0.0001, plus additional 2.96 +/- 1.8 mg of midazolam). Ephedrine was administered to 15 patients in Group M-P and 17 patients in Group P. Recovery was significantly fast (Group P, 6.8 +/- 2.9 min vs. Group M-P, 9.8 +/- 4.4 min, P<0.05). CONCLUSIONS: Sedation with propofol plus midazolam requires a lower total dose of propofol compared with propofol alone but has no superior hemodynamic stability. A further study using younger patients and combinations of different doses of each drug will be needed.